This invention relates to electrographic development apparatus having an improved ribbon blender for mixing developer material in a sump by providing feed members on a ribbon of the blender.
Commonly-assigned copending U.S. patent application Ser. No. 597 323, filed Apr. 6, 1984 in the names of Brian J. Joseph and Thomas K. Hilbert discloses an electrographic copier having a development station with a sump. Located within the sump is a ribbon blender that circulates developer material comprising carrier particles and toner particles axially within the sump to agitate and shear the developer material, promote tribocharging, and feed the developer out of the sump along a path that leads to a magnetic brush. In one embodiment of the apparatus disclosed in that application feeder vanes spaced radially outwardly from the blender pick up developer material in the sump and feed it from the sump directly to a magnetic brush located above the ribbon blender. The feeder vanes are spaced about the circumference of the ribbon blender, and each vane extends continuously from one end portion of the ribbon blender toward the other end thereof and above the convolutions of the ribbon blender. Such apparatus works well; however, if the cohesivity of the developer material is high, the feeder vanes tend to bore out a hole of cylindrical configuration in the developer material and the feeder vanes begin to trowell out the material around the circumference of that cylinder. Such can leave an area of developer material in the bottom of the sump that is not mixed and moved with the other developer material, resulting in packing of the developer material between the feeder vanes and the walls of the sump. This packed material connot be used for its intended purpose of developing images on the photoconductor and may have other adverse effects on the apparatus.